ABR

Definition & Etymology

ABR (Auditory Brainstem Response) is an objective, non-invasive electrophysiological test that records the neural activity from the auditory nerve (cranial nerve VIII) and brainstem pathways in response to acoustic stimuli, typically clicks or tone bursts. It is a type of auditory evoked potential (AEP). The term is descriptive, derived from the functions it measures: the auditory system’s response generated in the brainstem. It is also known as Brainstem Auditory Evoked Response (BAER) or Brainstem Auditory Evoked Potential (BAEP).

Clinical Significance

The ABR provides a reliable assessment of the integrity and function of the auditory pathway from the cochlea to the inferior colliculus in the brainstem. Its primary clinical application is in audiology and neurology for newborn hearing screening, estimating hearing thresholds in infants, young children, or individuals unable to participate in behavioral tests. It helps differentiate between conductive, cochlear (sensorineural), and retrocochlear (neural) pathologies. The test analyzes the latency and amplitude of a series of waves (I-V), each corresponding to a specific anatomical generator along the auditory pathway. ABR does not assess conscious hearing perception but rather the synchronous neural firing in the brainstem.

Related Conditions

ABR is a critical diagnostic tool for conditions including sensorineural hearing loss (SNHL) and auditory neuropathy spectrum disorder (ANSD), where cochlear function may be normal but neural transmission is impaired. It is also used in the evaluation of retrocochlear lesions such as acoustic neuromas (vestibular schwannomas), other brainstem tumors, and demyelinating diseases like multiple sclerosis. Abnormal ABR findings can prompt further neurodiagnostic imaging or investigation. It is a standard component of universal newborn hearing screening (UNHS) programs.

Key Takeaways

• ABR is an objective, electrophysiological measure of the auditory pathway’s integrity, not a direct test of subjective hearing.
• It is a cornerstone of universal newborn hearing screening and pediatric audiological assessment.
• The test is vital for identifying retrocochlear pathologies like acoustic neuromas and auditory neuropathy.

Note: This content is for informational purposes only and does not substitute for professional medical advice. Always consult your doctor for diagnosis and treatment.